


is a fish, will fight

by glowingjellyfishtreelights



Category: One Piece
Genre: mermaid au
Language: English
Status: In-Progress
Published: 2017-08-15
Updated: 2017-10-18
Packaged: 2018-12-15 17:51:23
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 2,139
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11811165
Author URL: https://archiveofourown.org/users/glowingjellyfishtreelights/pseuds/glowingjellyfishtreelights
Summary: Sabo wakes up somewhere he really doesn’t want to be, everything is probably always going to be Luffy’s fault even when it’s not, and Ace really does not think things through sometimes. (Okay, more like most of the time.)





	1. please do not pet the merman

**Author's Note:**

> fair warning if you're really super picky about how fish biology realistically would get mashed up with human biology you'll probably end up tearing out your hair at the stuff I write because my excuse for everything is going to be 'mythological creature'

Everything hurts and Sabo’s 95% certain it’s all Luffy’s fault.

All of it. Every bit of his foggy, unpleasantly pulsing brain, even as it’s clawing its way to semi-consciousness, is _convinced_ of the fact, and from the coppery tingling in his gills, the tug of scabbed-over cuts as his face automatically contorts- something strange about that, there- the way that he can’t really feel his arms or entire lower body, and the indistinct, blurry, mildly-agonized hazy lack of coherent memory when he takes a moment to try to think back to the last thing he remembers, he might as well go with it.

His brain might try and melt out of his ears if he tries to think any more, anyway.

 _Sea Kings_ , he hasn’t felt this cruddy since those first three weeks of dealing with both his suddenly changed biology _and_ poorly healing second and third degree burns.

(Sabo found it kind of funny though, years after the fact, that it took actually _getting_ burned for him to remember the correct order and severity of first-through-third burns. But mentioning that around his brothers those first few years tended to make Ace whap him upside the head and loudly call him morbid and/or weird while the water rapidly heated up around him and Luffy would ram into Sabo’s ribs and wrap him in a tangle of arms and many, many legs, sad face blatantly showcasing the guilt Ace did his (incredibly terrible) best attempt to hide.

Seeing as a sad Luffy is always a gut-churning sort of guilt-inducing experience that nobody enjoys, and Ace will tear himself apart with self-blame enough already without anyone helping that along, and then _Sabo_ gets all guilty about all that, leading into endless unpleasant ever-circling cycles, so Sabo took a rain check on that sort of thing.)

His body felt _heavy_. Every inch of it, even the non-numb parts. Like he’d become an anchor, being constantly dragged down. The strange, crackly, plastic-foam-y curve pressing into his shoulder-blades couldn’t cover the immovable, rock-hard surface it was apparently growing from.

If someone had put him on toxic sea-sponge again, Sabo was going to strangle them. With either the person’s own hair, tail, or a nearby, convenient strand of seaweed, depending on exactly how bad of a rash he was going to develop.

… Sea Kings all, his head _hurt_. The light filtering through his eyelids was _way_ too bright for his slow-building migraine, and _really_ wasn’t helping the overall faint nausea and other various unpleasant sensations he was starting to remember tended to come hand-in-hand with a concussion.

The fingers combing through his hair felt nice though. Even though something still felt-strange. Off. About everything. Maybe he wasn’t resting on toxic sea-sponges this time if they had brought him to Makino? She was the only one who did stuff like that. Had to be Makino.

… Please tell him he didn’t split his head open on a rock like Ace. If they _had_ brought him all the way to Makino- oh Sea Kings. He knocked himself out on a rock, didn’t he, even though swimming headfirst into rocks is supposed to be _Ace’s_ thing only, how do you even knock your head against a rock that hard unless he fell asleep while swimming, and that’s _only supposed to be Ace’s thing_ , Ace and Luffy will _never let him live this down_ -

Wait.

It is with a strong sense of relief that Sabo realizes that if he _had_ pulled an Ace (or, if we’re being honest, Luffy sometimes does it as well) and just fought a rock and lost, there was no possible way for the rest of his body to feel like he had just gone five rounds with Gramps. Or, from the most painful sections, the Lord Tiger Shark along with a pack of friends.

Only _Luffy_ could come away from a head-on collision with a rock and come away looking mauled. And that was only when he was way littler, like, when Ace had to go looking from shore-to-shore in tidal pools sometimes because he’d get trapped, littler.

The fingers gently tug a tangle out of his hair, and a strand flops onto his forehead, the loose curl tickling right above his eyebrow. The light’s still weirdly too bright through his lids, and his head still feels like Gramps decided to use his head and a Fist of Love to hammer out a two-minute drumbeat with his skull as the drum, but the fog’s clearing, a bit, and maybe he can move his arms-?

A very cautious, experimental shift from the shoulder-

 _PAIN_ OW BAD IDEA VERY BAD IDEA OW OW OW

The numbness burns away in a flash as all of his body’s nerves _scream_ at him, and Sabo jerks violently, eyes snapping open and then squinting hard as they get blinded instantly, his tail lashing out hard and hitting something with a hollow _thunk_ and a fresh wave of _oh lord why did you do that_ and water splashing up around his ribs- shallow water what the heck what was wrong with it why did it feel so lifeless- one arm crumpling beneath him, falling hard into the water like a slap to the face, sucking water sharply in through his gills but only one side, the other one gaping up in plain air- _there’s no sand moving was such a bad idea why is this glass or plastic or what (this is wrong not the sea where is this)????_

Rapidly clicking noises approaching then fading off and there’s voices, sharp and clear and without the oddly-tinged edges that he’s so used to and ohhhh crap no please he can’t possibly be where he thinks he is nope nope nope crap crap crap crap-

Sabo takes a gulp of (fake, fake and sterile not the ocean not even close) water, grits his teeth, and flips himself over.

The florescent lightbulbs stab into his eyes, but only for seconds before his eyes shift to adjust (oh hey guess it wasn’t a concussion after all that’s probably a good thing), dangling down from the gray ceiling’s beams, erratically blocked by the dizzy-spots still floating in his vision, long hair hovering in barely in his sight on the side of his good eye-

Hanging _down_ , not floating, and this is a _horseshoe_ _crab_ , or, or, a _ray petting_ tank with the edges covered in brightly colored pool noodles and there’s too-flat _walls_ and a _floor_ and a deceptively innocent pair of brightly colored flip-flops sitting right at the corner of his eye right next to a _book_ -

There’s a face right above his.

Sabo blinks up, wide-eyed, at the young woman’s face hovering less than a yard above his.

The young woman blinks back, her honey-brown ponytail slowly sliding over her shoulder, frozen in an awkward, half-risen crouch. Because she has knees, and is getting up from apparently having knelt beside him, stroking his hair. Which means legs. Which means feet. Which means _human_ -

There is a moment of complete and utter silence and stillness. Two different species, making stunned eye contact for the first time. Then…

_“YEEARGH!”_

_“GAHH!”_

There is absolutely no way this is not somehow Luffy’s fault.

And once Sabo’s finished trying to shove himself out of human-reaching-range in a flailing panic, heart pounding in his throat so hard it almost feels like he’s going to choke on it, he’s going to make sure he _pays_ for it.

 

(He will deny to his dying day that his yelp was of roughly equal pitch to the young woman's as they each reflexively threw themselves out of reach.

No one will ever be allowed to know.

 _Ever._ )

 


	2. ain't human bodies just great

**Notes for the Chapter:**

> so remember back when I was hoping trying to figure out a multi-chapter fic would nudge me into writing more ahaha yeah that sure worked didn't it

Okay.

So Ace _might_ not have thought every detail of this whole rescue thing totally through.

( ~~at all~~ )

His chin crashed against the ground again, this time managing catch his tongue between his teeth. His next bout of cursing was distorted by clumsy attempts to keep it from touching against anything and spitting out a coppery-tainted mouthful of sand, eyes stinging even as he screwed them tightly shut.

Poseidon, Triton, and Amphitrite, why was this so hard?! Sabo never had any problems moving around on land when he was human!

Ace twisted around to glare at the useless, stupid, shaky appendages called ‘legs’ sprawled out innocently on the sand where his tail should be. The bendy part in the middle of one- a knee? An ankle? Sea Kings, Ace doesn’t even care, it doesn’t work right anyway- is scraped and oozing a little, beading up strangely. It’s gross. Ace kind of wants to touch it.

He resists, because he’s not Luffy.

This was a _mess_. First he almost drowned because human bodies are _stupid_ and only have one respiratory system- now he knows why humans panic so much when they fall in, Sea Kings all, that was _horrible_ \- then after he dragged himself up to the shore, he spent a thoroughly uncomfortable _age_ trying to hack up the water. It _burned_. His lungs still ached.

He no longer wondered why humans were everywhere but only occasionally went into the sea. He doesn’t think he’s every felt the water so unfriendly before. Not even that time near the pollution patch.

Now, he’s stuck on his belly in the sand, grit rubbing uncomfortably where it slipped between and stuck on the floppy, draggy human garments the spell slapped on him- and those felt weird enough already- and because of course it would fit right in with his lifetime of bad luck, either something in the couple-hundreds-of-years-old disguise spell that had been reliably used for centuries (though sparingly) was messed up, or he screwed something up by like, casting it underwater, or something, because the _stupid human legs weren’t working_.

“Maybe it’s your fault,” Ace grumbled under his breath, wincing as his sore tongue bumped against the roof of his mouth, tugging at the fabric plastered against his skin. One of the dryer sections crackled in response to the movement, sending little grains of sand happily bouncing down to the ground again.

Stupid ‘clothing’ screwing up his frantic attempts at swimming to surface. Stupid broken human bodies. Stupid Sabo for getting himself torn up by the Tiger-fish-Lord and then getting snatched by a bunch of humans.

Stupid _Ace_ for not being there to save him.

No. Stop. Not going down that again. Got a job to do. Ace shook his head hard, and forced his brain back to Sabo.

Okay. So he was successfully on land. That was the part he’d been the most worried about, and the only one he had to worry about being caught on. He hadn’t been caught stealing the spell, swimming out to an isolated spot close to the shore, and working it. He was out of Gramps’s reach.

Now he had to find a way to move, find Sabo, and get him back to the ocean. Ace still had the wadded-up woven original disguise spell stuffed in one of the garment pouches- since Sabo knew how to be human from before, he’d probably be a lot better at it than Ace, and he could move pretty fast back then, too (somehow) even though it wasn’t as fast as swimming. He could work it, they’d sneak back to the ocean, they work the undo on the backside of the spell, and they’ll be back before Luffy sneaks back from Makino’s cave.

It shouldn’t be hard to find Sabo. Ace very carefully dragged his legs up closer to his body, arranging the feet the way he foggily remembered Sabo’s being positioned when he was standing, and tried slowly pulling himself upright on the nearby rock again. All he had to do was follow the fuss of a ‘Merman’ being found- it was ordinary fisher-folk who’d dragged Sabo up, Luffy had said, not uniforms. There was no way it wouldn’t be everywhere.

He was upright. Ace grinned. His legs still felt weird, kind of shaky, but they weren’t cramping anymore. Maybe they just needed time? He let go of the rock slowly.

His legs may as well have been seaweed for all the use they were. Seriously.

At least he avoided getting any sand in his mouth this time. Clipped his elbow on the rock, but still. Small victories?

“Oi, kid, you okay over there?”

… _Fffffff_ reaking trash piles.

(Oh Sea Kings, Makino got to him enough he can’t even cuss in his own head without hastily censoring himself and feeling guilty about it even when he’s about to die how did that happen)

Ace’s head snapped up and he almost inhaled the sand falling from his face as he stared up at the approaching _humans_ towering above him.

And up, and up, and up.

Holy _crap_ that guy might be bigger than _Gramps_.

He’s so dead.

**Notes for the Chapter:**

> ... I don't exactly remember what my initial plans from the first chapter were anymore.  
>  oops?
> 
> EDIT: welp dang those notes from the first chapter aren't supposed to be there. hm.

**Author's Note:**

> so yeah this is just me trying to figure out how multiple chapters work, how adding tags and stuff as you go works, and also developing the Mer Au I've had floating aimlessly around for a while.
> 
> Also I'm pretty sure I misused the word 'biology' but meh


End file.
